To say that software is math doesn't really tell the whole story, though. In this sense, the word "Math" is being used in two different ways. The "Math" that is discovered (and thus not patentable) is the kind that tells us things about orders of infinity, and the countability of natural numbers.

The math that is used for software construction isn't discovering anything, it's constructing something. I think no one would argue that anyone "discovered" Linux, or Office. These things were built to fulfill a purpose, and serve a useful function. This also separates them from a story-book. That's why the patent question for software is so interesting, I think.